382 BOTANICAL GAZETTE [juxe 



again gave the same mycelium and conidia as had been obtained 

 from the imperfect stage. 



While there are some slight differences between this form and the. 

 one from sycamore in the size of the conidia and effect on culture 

 media, these do not seem to be sufficient to make a new species, 

 especially since the large conidia do not appear on artificial media. 

 Perhaps the slight difference found on culture media was due to the 

 previous growth for some time on different hosts. The one from 

 white oak, after being grown for several months on artificial media, 

 lost some of the characters it originally had. The zonate growth of 

 the colony became less marked, and the aerial tufts containing pustules 

 were more feebly developed. The difference between the forms on 

 Quercus velutina and Plalanus occidenlalis was, perhaps, no more 

 marked than the difference between cultures of the same fungus after 

 growing for different periods on artificial media. 



Search on other oaks has also resulted in finding the Myxosporium 

 stage on twigs of Quercus coccinea. The disease was not different 

 in appearance from that on the other hosts, and a culture of the spores 

 also gave a colony similar to the colonies from other hosts. Anthrac 

 nosed leaves of Q. coccinea have not been found, but they undoubtedly 

 can be found at the right season. 



While no satisfactory inoculation experiments were carried on, 

 it seems almost certain that these three forms are the same. They 

 are at least no more than biological species. Attempts were made 

 to inoculate young oaks in the greenhouse, but they were unsuccessful, 

 even when the conidia were placed on the same species of oak from 

 which they were developed. 



WTiether Gnomonia veneta occurs on any other host is a question; 

 there appears no reason why it should not be found on other oaks. 

 Halsted (16) has described the disease as occurring on red maple 

 {Acer ruhrum). While this is very possible, proof of it will only 

 appear when the perfect stage is developed and the forms are com- 

 pared on culture media. No Gloeosnoriiirr. Tin^ K^ph fn,inr1 nn manle 



near 



chance to find the perfect stage. How 



^_^ 



stran 



on the other hosts. 



